(function ($) {
  $.fn.downCount = function (options, callback) {
    var settings = $.extend({
      date: null,
      offset: null
    }, options);
    if (!settings.date) {
      $.error('Date is not defined.');
    }
    if (!Date.parse(settings.date)) {
      $.error('Incorrect date format, it should look like this, 12/24/2012 12:00:00.');
    }
    var container = this;
    var currentDate = function () {
      var date = new Date();
      /*var utc = date.getTime() + (date.getTimezoneOffset() * 60000);
      var new_date = new Date(utc + (3600000*settings.offset));*/
      return date;
    };
    function countdown () {
      var target_date = new Date(settings.date),
        current_date = currentDate();
      var difference = target_date - current_date;
      if (difference < 0) {
        clearInterval(interval);//取消 setInterval() 函数设定的定时执行操作
        if (callback && typeof callback === 'function') callback();
        return;
      }
      var _second = 1000,
        _minute = _second * 60,
        _hour = _minute * 60,
        _day = _hour * 24;
      var days = Math.floor(difference / _day),
        hours = Math.floor(((difference % _day) / _hour) + (days*24)),
        minutes = Math.floor((difference % _hour) / _minute),
        seconds = Math.floor((difference % _minute) / _second);
      days = (String(days).length >= 2) ? days : '0' + days;
      hours = (String(hours).length >= 2) ? hours : '0' + hours;
      minutes = (String(minutes).length >= 2) ? minutes : '0' + minutes;
      seconds = (String(seconds).length >= 2) ? seconds : '0' + seconds;
      container.find('.hours').text(hours);
      container.find('.minutes').text(minutes);
      container.find('.seconds').text(seconds);
    };
    var interval = setInterval(countdown, 1000);
  };
})(jQuery);